Problem Statement: The tension between the requirements of modern urban development (commercialization and tourism infrastructure) and the necessity of preserving architectural heritage threatens the integrity of the historical contexts of Tabriz and Yazd. The lack of accurate documentation and weak implementation of conservation laws have also exacerbated this crisis. Objectives: To quantitatively and qualitatively analyze the destructive effects of development on architectural heritage, identify spatial patterns of destruction, and evaluate the effectiveness of existing conservation frameworks. Research Question: How do commercial and tourism development projects affect the authenticity and integrity of the historical contexts of Tabriz and Yazd, and what physical, economic, and social mechanisms lie behind these destructive processes.Research hypothesis: Accelerated development and the political economy of space, through the creation of physical and functional changes at the micro scale, systematically lead to macro-destruction and violation of the integrity of historical textures. Research method: This research has used the "combination with sequential explanatory design" method and based on the "Historic Urban Landscape (HUL)" paradigm. In the quantitative phase, 156 heritage plaques as "urban sensors" were subjected to field surveys and GIS analysis. In the qualitative phase, using the "nested sampling" strategy and focusing on "deviant cases", 47 interviews were conducted with stakeholders of the plaques with the most destruction so that the micro-observations can be generalized inductively.Conclusion: The findings confirm that micro-changes have systematically caused macro-destructive transformation; such that 34.6% of the samples in Tabriz (mainly commercial regeneration in the bazaar) and 28.6% in Yazd (hastily built hotels in Fahadan) have suffered structural degradation. The study identifies three main mechanisms including “hidden degradation”, “structural instability” and “gentrification” and emphasizes the need for an urgent transition to a HUL conservation approach.